diff --git a/src/ZoneTree/Comparers/ByteArrayComparerAscending.cs b/src/ZoneTree/Comparers/ByteArrayComparerAscending.cs
index 027dadf..ef496a5 100644
--- a/src/ZoneTree/Comparers/ByteArrayComparerAscending.cs
+++ b/src/ZoneTree/Comparers/ByteArrayComparerAscending.cs
@@ -9,7 +9,7 @@ public int Compare(in Memory<byte> x, in Memory<byte> y)
         var spanY = y.Span;
         for (var i = 0; i < len; ++i)
         {
-            var r = spanX[i] - spanY[i];
+            var r = spanX[i].CompareTo(spanY[i]);
             if (r < 0)
                 return -1;
             if (r > 0)
diff --git a/src/ZoneTree/Comparers/ByteArrayComparerDescending.cs b/src/ZoneTree/Comparers/ByteArrayComparerDescending.cs
index 3871a0a..da3befe 100644
--- a/src/ZoneTree/Comparers/ByteArrayComparerDescending.cs
+++ b/src/ZoneTree/Comparers/ByteArrayComparerDescending.cs
@@ -9,7 +9,7 @@ public int Compare(in Memory<byte> x, in Memory<byte> y)
         var spanY = y.Span;
         for (var i = 0; i < len; ++i)
         {
-            var r = spanY[i] - spanX[i];
+            var r = spanY[i].CompareTo(spanX[i]);
             if (r < 0)
                 return -1;
             if (r > 0)
diff --git a/src/ZoneTree/Comparers/ByteComparerAscending.cs b/src/ZoneTree/Comparers/ByteComparerAscending.cs
index 63af02e..44cde98 100644
--- a/src/ZoneTree/Comparers/ByteComparerAscending.cs
+++ b/src/ZoneTree/Comparers/ByteComparerAscending.cs
@@ -4,6 +4,6 @@ public sealed class ByteComparerAscending : IRefComparer<byte>
 {
     public int Compare(in byte x, in byte y)
     {
-        return x - y;
+        return x.CompareTo(y);
     }
 }
diff --git a/src/ZoneTree/Comparers/CharComparerAscending.cs b/src/ZoneTree/Comparers/CharComparerAscending.cs
index 9666ef5..4d3ab15 100644
--- a/src/ZoneTree/Comparers/CharComparerAscending.cs
+++ b/src/ZoneTree/Comparers/CharComparerAscending.cs
@@ -4,6 +4,6 @@ public sealed class CharComparerAscending : IRefComparer<char>
 {
     public int Compare(in char x, in char y)
     {
-        return x - y;
+        return x.CompareTo(y);
     }
 }
diff --git a/src/ZoneTree/Comparers/DateTimeComparerAscending.cs b/src/ZoneTree/Comparers/DateTimeComparerAscending.cs
index c7abc5c..5e247ea 100644
--- a/src/ZoneTree/Comparers/DateTimeComparerAscending.cs
+++ b/src/ZoneTree/Comparers/DateTimeComparerAscending.cs
@@ -4,9 +4,6 @@ public sealed class DateTimeComparerAscending : IRefComparer<DateTime>
 {
     public int Compare(in DateTime x, in DateTime y)
     {
-        var r = x.Ticks - y.Ticks;
-        if (r == 0)
-            return 0;
-        return r < 0 ? -1 : 1;
+        return x.CompareTo(y);
     }
 }
\ No newline at end of file
diff --git a/src/ZoneTree/Comparers/DateTimeComparerDescending.cs b/src/ZoneTree/Comparers/DateTimeComparerDescending.cs
index 8b21b31..ca8e7a7 100644
--- a/src/ZoneTree/Comparers/DateTimeComparerDescending.cs
+++ b/src/ZoneTree/Comparers/DateTimeComparerDescending.cs
@@ -4,9 +4,6 @@ public sealed class DateTimeComparerDescending : IRefComparer<DateTime>
 {
     public int Compare(in DateTime x, in DateTime y)
     {
-        var r = y.Ticks - x.Ticks;
-        if (r == 0)
-            return 0;
-        return r < 0 ? -1 : 1;
+        return y.CompareTo(x);
     }
 }
\ No newline at end of file
diff --git a/src/ZoneTree/Comparers/DecimalComparerAscending.cs b/src/ZoneTree/Comparers/DecimalComparerAscending.cs
index 50df086..4cba0d0 100644
--- a/src/ZoneTree/Comparers/DecimalComparerAscending.cs
+++ b/src/ZoneTree/Comparers/DecimalComparerAscending.cs
@@ -4,9 +4,6 @@ public sealed class DecimalComparerAscending : IRefComparer<decimal>
 {
     public int Compare(in decimal x, in decimal y)
     {
-        var r = x - y;
-        if (r == 0)
-            return 0;
-        return r < 0 ? -1 : 1;
+        return x.CompareTo(y);
     }
 }
diff --git a/src/ZoneTree/Comparers/DecimalComparerDescending.cs b/src/ZoneTree/Comparers/DecimalComparerDescending.cs
new file mode 100644
index 0000000..5e3308a
--- /dev/null
+++ b/src/ZoneTree/Comparers/DecimalComparerDescending.cs
@@ -0,0 +1,9 @@
+namespace Tenray.ZoneTree.Comparers;
+
+public sealed class DecimalComparerDescending : IRefComparer<decimal>
+{
+    public int Compare(in decimal x, in decimal y)
+    {
+        return y.CompareTo(x);
+    }
+}
\ No newline at end of file
diff --git a/src/ZoneTree/Comparers/DoubleComparerAscending.cs b/src/ZoneTree/Comparers/DoubleComparerAscending.cs
index 27a3a8c..4482032 100644
--- a/src/ZoneTree/Comparers/DoubleComparerAscending.cs
+++ b/src/ZoneTree/Comparers/DoubleComparerAscending.cs
@@ -4,9 +4,6 @@ public sealed class DoubleComparerAscending : IRefComparer<double>
 {
     public int Compare(in double x, in double y)
     {
-        var r = x - y;
-        if (r == 0)
-            return 0;
-        return r < 0 ? -1 : 1;
+        return x.CompareTo(y);
     }
 }
\ No newline at end of file
diff --git a/src/ZoneTree/Comparers/DoubleComparerDescending.cs b/src/ZoneTree/Comparers/DoubleComparerDescending.cs
index e76b218..f772d6c 100644
--- a/src/ZoneTree/Comparers/DoubleComparerDescending.cs
+++ b/src/ZoneTree/Comparers/DoubleComparerDescending.cs
@@ -1,12 +1,9 @@
 namespace Tenray.ZoneTree.Comparers;
 
-public sealed class DoubleComparerDescending: IRefComparer<double>
+public sealed class DoubleComparerDescending : IRefComparer<double>
 {
     public int Compare(in double x, in double y)
     {
-        var r = y - x;
-        if (r == 0)
-            return 0;
-        return r < 0 ? -1 : 1;
+        return y.CompareTo(x);
     }
 }
\ No newline at end of file
diff --git a/src/ZoneTree/Comparers/Int16ComparerAscending.cs b/src/ZoneTree/Comparers/Int16ComparerAscending.cs
index 85ddf1c..d843d00 100644
--- a/src/ZoneTree/Comparers/Int16ComparerAscending.cs
+++ b/src/ZoneTree/Comparers/Int16ComparerAscending.cs
@@ -4,6 +4,6 @@ public sealed class Int16ComparerAscending : IRefComparer<short>
 {
     public int Compare(in short x, in short y)
     {
-        return x - y;
+        return x.CompareTo(y);
     }
-}
\ No newline at end of file
+}
diff --git a/src/ZoneTree/Comparers/Int16ComparerDescending.cs b/src/ZoneTree/Comparers/Int16ComparerDescending.cs
index 5c04187..5968b66 100644
--- a/src/ZoneTree/Comparers/Int16ComparerDescending.cs
+++ b/src/ZoneTree/Comparers/Int16ComparerDescending.cs
@@ -4,6 +4,6 @@ public sealed class Int16ComparerDescending : IRefComparer<short>
 {
     public int Compare(in short x, in short y)
     {
-        return y - x;
+        return y.CompareTo(x);
     }
-}
\ No newline at end of file
+}
diff --git a/src/ZoneTree/Comparers/Int32ComparerAscending.cs b/src/ZoneTree/Comparers/Int32ComparerAscending.cs
index 0767f8c..70a12ae 100644
--- a/src/ZoneTree/Comparers/Int32ComparerAscending.cs
+++ b/src/ZoneTree/Comparers/Int32ComparerAscending.cs
@@ -4,6 +4,6 @@ public sealed class Int32ComparerAscending : IRefComparer<int>
 {
     public int Compare(in int x, in int y)
     {
-        return x - y;
+        return x.CompareTo(y);
     }
 }
diff --git a/src/ZoneTree/Comparers/Int32ComparerDescending.cs b/src/ZoneTree/Comparers/Int32ComparerDescending.cs
index 56f46fa..4ab7530 100644
--- a/src/ZoneTree/Comparers/Int32ComparerDescending.cs
+++ b/src/ZoneTree/Comparers/Int32ComparerDescending.cs
@@ -4,6 +4,6 @@ public sealed class Int32ComparerDescending : IRefComparer<int>
 {
     public int Compare(in int x, in int y)
     {
-        return y - x;
+        return y.CompareTo(x);
     }
 }
diff --git a/src/ZoneTree/Comparers/Int64ComparerAscending.cs b/src/ZoneTree/Comparers/Int64ComparerAscending.cs
index 4518d1e..cf4c4aa 100644
--- a/src/ZoneTree/Comparers/Int64ComparerAscending.cs
+++ b/src/ZoneTree/Comparers/Int64ComparerAscending.cs
@@ -4,9 +4,6 @@ public sealed class Int64ComparerAscending : IRefComparer<long>
 {
     public int Compare(in long x, in long y)
     {
-        var r = x - y;
-        if (r == 0)
-            return 0;
-        return r < 0 ? -1 : 1;
+        return x.CompareTo(y);
     }
 }
diff --git a/src/ZoneTree/Comparers/Int64ComparerDescending.cs b/src/ZoneTree/Comparers/Int64ComparerDescending.cs
index a6e096c..fdbe900 100644
--- a/src/ZoneTree/Comparers/Int64ComparerDescending.cs
+++ b/src/ZoneTree/Comparers/Int64ComparerDescending.cs
@@ -4,9 +4,6 @@ public sealed class Int64ComparerDescending : IRefComparer<long>
 {
     public int Compare(in long x, in long y)
     {
-        var r = y - x;
-        if (r == 0)
-            return 0;
-        return r < 0 ? -1 : 1;
+        return y.CompareTo(x);
     }
-}
\ No newline at end of file
+}
diff --git a/src/ZoneTree/Comparers/UInt16ComparerAscending.cs b/src/ZoneTree/Comparers/UInt16ComparerAscending.cs
new file mode 100644
index 0000000..3ccee75
--- /dev/null
+++ b/src/ZoneTree/Comparers/UInt16ComparerAscending.cs
@@ -0,0 +1,9 @@
+namespace Tenray.ZoneTree.Comparers;
+
+public sealed class UInt16ComparerAscending : IRefComparer<ushort>
+{
+    public int Compare(in ushort x, in ushort y)
+    {
+        return x.CompareTo(y);
+    }
+}
\ No newline at end of file
diff --git a/src/ZoneTree/Comparers/UInt16ComparerDescending.cs b/src/ZoneTree/Comparers/UInt16ComparerDescending.cs
new file mode 100644
index 0000000..570ad71
--- /dev/null
+++ b/src/ZoneTree/Comparers/UInt16ComparerDescending.cs
@@ -0,0 +1,9 @@
+namespace Tenray.ZoneTree.Comparers;
+
+public sealed class UInt16ComparerDescending : IRefComparer<ushort>
+{
+    public int Compare(in ushort x, in ushort y)
+    {
+        return y.CompareTo(x);
+    }
+}
\ No newline at end of file
diff --git a/src/ZoneTree/Comparers/UInt32ComparerAscending.cs b/src/ZoneTree/Comparers/UInt32ComparerAscending.cs
new file mode 100644
index 0000000..f769424
--- /dev/null
+++ b/src/ZoneTree/Comparers/UInt32ComparerAscending.cs
@@ -0,0 +1,9 @@
+namespace Tenray.ZoneTree.Comparers;
+
+public sealed class UInt32ComparerAscending : IRefComparer<uint>
+{
+    public int Compare(in uint x, in uint y)
+    {
+        return x.CompareTo(y);
+    }
+}
diff --git a/src/ZoneTree/Comparers/UInt32ComparerDescending.cs b/src/ZoneTree/Comparers/UInt32ComparerDescending.cs
new file mode 100644
index 0000000..314e7fa
--- /dev/null
+++ b/src/ZoneTree/Comparers/UInt32ComparerDescending.cs
@@ -0,0 +1,9 @@
+namespace Tenray.ZoneTree.Comparers;
+
+public sealed class UInt32ComparerDescending : IRefComparer<uint>
+{
+    public int Compare(in uint x, in uint y)
+    {
+        return y.CompareTo(x);
+    }
+}
diff --git a/src/ZoneTree/Comparers/UInt64ComparerAscending.cs b/src/ZoneTree/Comparers/UInt64ComparerAscending.cs
new file mode 100644
index 0000000..aab080d
--- /dev/null
+++ b/src/ZoneTree/Comparers/UInt64ComparerAscending.cs
@@ -0,0 +1,9 @@
+namespace Tenray.ZoneTree.Comparers;
+
+public sealed class UInt64ComparerAscending : IRefComparer<ulong>
+{
+    public int Compare(in ulong x, in ulong y)
+    {
+        return x.CompareTo(y);
+    }
+}
\ No newline at end of file
diff --git a/src/ZoneTree/Comparers/UInt64ComparerDescending.cs b/src/ZoneTree/Comparers/UInt64ComparerDescending.cs
new file mode 100644
index 0000000..027828b
--- /dev/null
+++ b/src/ZoneTree/Comparers/UInt64ComparerDescending.cs
@@ -0,0 +1,9 @@
+namespace Tenray.ZoneTree.Comparers;
+
+public sealed class UInt64ComparerDescending : IRefComparer<ulong>
+{
+    public int Compare(in ulong x, in ulong y)
+    {
+        return y.CompareTo(x);
+    }
+}
\ No newline at end of file
diff --git a/src/ZoneTree/Core/ZoneTree.BottomSegments.Merge.cs b/src/ZoneTree/Core/ZoneTree.BottomSegments.Merge.cs
index dbcbdf6..d8700cd 100644
--- a/src/ZoneTree/Core/ZoneTree.BottomSegments.Merge.cs
+++ b/src/ZoneTree/Core/ZoneTree.BottomSegments.Merge.cs
@@ -77,6 +77,9 @@ MergeResult MergeBottomSegmentsInternal(int from, int to)
 
         var writeDeletedValues = from > 0;
 
+        if (to > BottomSegments.Count)
+            to = BottomSegments.Count;
+
         var mergingSegments = bottomSegments
             .Select(x => x.GetSeekableIterator())
             .Skip(from)
diff --git a/src/ZoneTree/Serializers/Int16Serializer.cs b/src/ZoneTree/Serializers/Int16Serializer.cs
index 2a79030..151b987 100644
--- a/src/ZoneTree/Serializers/Int16Serializer.cs
+++ b/src/ZoneTree/Serializers/Int16Serializer.cs
@@ -11,4 +11,4 @@ public Memory<byte> Serialize(in short entry)
     {
         return BitConverter.GetBytes(entry);
     }
-}
\ No newline at end of file
+}
diff --git a/src/ZoneTree/Serializers/UInt16Serializer.cs b/src/ZoneTree/Serializers/UInt16Serializer.cs
new file mode 100644
index 0000000..dba5215
--- /dev/null
+++ b/src/ZoneTree/Serializers/UInt16Serializer.cs
@@ -0,0 +1,14 @@
+namespace Tenray.ZoneTree.Serializers;
+
+public sealed class UInt16Serializer : ISerializer<ushort>
+{
+    public ushort Deserialize(Memory<byte> bytes)
+    {
+        return BitConverter.ToUInt16(bytes.Span);
+    }
+
+    public Memory<byte> Serialize(in ushort entry)
+    {
+        return BitConverter.GetBytes(entry);
+    }
+}
\ No newline at end of file
diff --git a/src/ZoneTree/Serializers/UInt32Serializer.cs b/src/ZoneTree/Serializers/UInt32Serializer.cs
new file mode 100644
index 0000000..2c406fc
--- /dev/null
+++ b/src/ZoneTree/Serializers/UInt32Serializer.cs
@@ -0,0 +1,14 @@
+namespace Tenray.ZoneTree.Serializers;
+
+public sealed class UInt32Serializer : ISerializer<uint>
+{
+    public uint Deserialize(Memory<byte> bytes)
+    {
+        return BitConverter.ToUInt32(bytes.Span);
+    }
+
+    public Memory<byte> Serialize(in uint entry)
+    {
+        return BitConverter.GetBytes(entry);
+    }
+}
\ No newline at end of file
diff --git a/src/ZoneTree/Serializers/UInt64Serializer.cs b/src/ZoneTree/Serializers/UInt64Serializer.cs
new file mode 100644
index 0000000..17aff9b
--- /dev/null
+++ b/src/ZoneTree/Serializers/UInt64Serializer.cs
@@ -0,0 +1,14 @@
+namespace Tenray.ZoneTree.Serializers;
+
+public sealed class UInt64Serializer : ISerializer<ulong>
+{
+    public ulong Deserialize(Memory<byte> bytes)
+    {
+        return BitConverter.ToUInt64(bytes.Span);
+    }
+
+    public Memory<byte> Serialize(in ulong entry)
+    {
+        return BitConverter.GetBytes(entry);
+    }
+}
diff --git a/src/ZoneTree/ZoneTreeFactory.cs b/src/ZoneTree/ZoneTreeFactory.cs
index 3d32d5f..085bab7 100644
--- a/src/ZoneTree/ZoneTreeFactory.cs
+++ b/src/ZoneTree/ZoneTreeFactory.cs
@@ -364,8 +364,11 @@ void FillComparer()
             decimal => new DecimalComparerAscending() as IRefComparer<TKey>,
             double => new DoubleComparerAscending() as IRefComparer<TKey>,
             short => new Int16ComparerAscending() as IRefComparer<TKey>,
+            ushort => new UInt16ComparerAscending() as IRefComparer<TKey>,
             int => new Int32ComparerAscending() as IRefComparer<TKey>,
+            uint => new UInt32ComparerAscending() as IRefComparer<TKey>,
             long => new Int64ComparerAscending() as IRefComparer<TKey>,
+            ulong => new UInt64ComparerAscending() as IRefComparer<TKey>,
             Guid => new GuidComparerAscending() as IRefComparer<TKey>,
             _ => null
         };
@@ -391,8 +394,11 @@ void FillKeySerializer()
             decimal => new DecimalSerializer() as ISerializer<TKey>,
             double => new DoubleSerializer() as ISerializer<TKey>,
             short => new Int16Serializer() as ISerializer<TKey>,
+            ushort => new UInt16Serializer() as ISerializer<TKey>,
             int => new Int32Serializer() as ISerializer<TKey>,
+            uint => new UInt32Serializer() as ISerializer<TKey>,
             long => new Int64Serializer() as ISerializer<TKey>,
+            ulong => new UInt64Serializer() as ISerializer<TKey>,
             Guid => new StructSerializer<Guid>() as ISerializer<TKey>,
             _ => null
         };
@@ -425,8 +431,11 @@ void FillValueSerializer()
             decimal => new DecimalSerializer() as ISerializer<TValue>,
             double => new DoubleSerializer() as ISerializer<TValue>,
             short => new Int16Serializer() as ISerializer<TValue>,
+            ushort => new UInt16Serializer() as ISerializer<TValue>,
             int => new Int32Serializer() as ISerializer<TValue>,
+            uint => new UInt32Serializer() as ISerializer<TValue>,
             long => new Int64Serializer() as ISerializer<TValue>,
+            ulong => new UInt64Serializer() as ISerializer<TValue>,
             Guid => new StructSerializer<Guid>() as ISerializer<TValue>,
             _ => null
         };